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Variation of sex differentiation
Published in Joseph S. Sanfilippo, Eduardo Lara-Torre, Veronica Gomez-Lobo, Sanfilippo's Textbook of Pediatric and Adolescent GynecologySecond Edition, 2019
Anne-Marie Amies Oelschlager, Margarett Shnorhavorian
Complete gonadal dysgenesis with a 46,XY karyotype is the result of failure of the gonadal tissues to develop into functioning testicular tissue. As a result, there is no Sertoli production of AMH and no Leydig cell production of testosterone. Müllerian structures develop, and external genitalia appear typical for a female. This clinical condition is named Swyer syndrome. Often these individuals are identified with pubertal delay and elevated gonadotropins or when they present with a gonadoblastoma. SRY gene mutations have been identified in 15% of individuals with Swyer syndrome. Additional mutations associated with 46,XY complete gonadal dysgenesis have been identified in the MAP3K1, DHH, and NR5A1 genes (Table 7.1).
Hormonal control of the menstrual cycle and hormonal disorders
Published in Helen Bickerstaff, Louise C Kenny, Gynaecology, 2017
In this situation, the gonads do not develop into a testis, despite the presence of an XY karyotype. In about 15% of cases, this is due to a mutation in the SRY gene on the Y chromosome, but in most cases the cause is unknown. In complete gonadal dysgenesis (Swyer syndrome), the gonad remains as a streak gonad and does not produce any hormones. In the absence of anti-Müllerian hormone (AMH), the Müllerian structures do not regress and the uterus, vagina and Fallopian tubes develop normally. The absence of testosterone means the fetus does not virilize. The baby is phenotypically female, although has an XY chromosome. The gonads do not function and presentation is usually at adolescence with delayed puberty. The dysgenetic gonad has a high malignancy risk and should be removed when the diagnosis is made. This is usually performed laparoscopically. Puberty must be induced with oestrogen and pregnancies have been reported with a donor oocyte. Full disclosure of the diagnosis including the XY karytoype is essential, although this can be devastating and specialized psychological input is crucial.
Familial Swyer syndrome: a rare genetic entity
Published in Gynecological Endocrinology, 2018
Manilal Banoth, Ramana Reddy Naru, Mohammed Basheeruddin Inamdar, Amit Kumar Chowhan
Swyer syndrome was first recognized in 1955 when Gim Swyer described two cases of sex reversal that differed from the known forms of what was then termed "male pseudohermaphroditism"[1]. It is characterized by a 46, XY karyotype, normal female external genitalia, completely undeveloped (streak) gonads, no sperm production, hypergonadotropic hypogonadism (secondary to gonadal failure) and presence of normal Mullerian structures (uterus, fallopian tubes, and vagina) [2]. These individuals are typically raised as females and have a female gender identity. Swyer syndrome has been estimated to occur in approximately in 1 in 100000 people [3]. The diagnosis relies on clinical findings, chromosome analysis, and testing to detect changes in one of the following genes: SRY, NR5A1, DHH, NR0B1, or WNT4 [5]. Mutations in the SRY gene have been identified in between 15%–20% of individuals with this condition. These mutations prevent production of the sex-determining region Y protein or resulting the production of a nonfunctioning protein. A fetus whose cells do not produce functional sex-determining region Y protein will develop as a female, despite having a Y chromosome. In the remaining 80–90% of cases, the SRY gene is normal and mutations in other genes are probably implicated. Most cases of SRY-related Swyer syndrome result from new mutations and occur in people with no history of the disorder in their family. The condition usually first becomes apparent in adolescence with delayed puberty and primary amenorrhea due to the fact that the gonads have no hormonal or reproductive potential [2]. Swyer syndrome can be inherited in an autosomal dominant (NR5A1 mutations, heterozygous mutations in DHH, WNT4 duplications), autosomal recessive (homozygous [or compound heterozygous] mutations in DHH), X-linked (NR0B1 duplications) or Y-linked (SRY mutations) manner depending on the gene involved [6].
Twin gestation in a Swyer syndrome patient with superimposed pre-eclampsia
Published in Journal of Obstetrics and Gynaecology, 2018
Jaimin S. Shah, Oscar A. Viteri, Monica Longo, Mazen Abdallah, Baha Sibai
Since 1989, there have been 24 reported women with Swyer syndrome (SS) achieving successful pregnancies using fresh donor oocyte (FDO) in vitro fertilisation (IVF) (Kalra et al. 2016). Of these, two patients had chronic hypertension (cHTN), one of whom developed superimposed pre-eclampsia with severe features (SIPIH). We report a case of a 39-year-old woman who underwent FDO IVF, resulting in a twin gestation complicated by SIPIH.
Unexpected diagnosis of stage IIA dysgerminoma in streak gonad in a patient with Swyer syndrome: a case report
Published in Gynecological Endocrinology, 2018
Namiko Yada-Hashimoto, Hiroko Komura, Shigenori Nagata, Chiaki Kubo, Masami Fujita, Shoji Kamiura
In 1955, Swyer reported two cases of sex reversal that had a 46,XY karyotype. These cases had primary amenorrhea, tall stature, female external genitalia, and normal Mullerian structures [1]. Swyer syndrome is one of the Y-chromosome-related disorders of sex development (DSD). The patients are females phenotypically with a 46,XY karyotype. It is a rare form of gonadal dysgenesis that affects 5/100,000 live births.